[Acute effects of ibopamine on left ventricular mechanics and contractility in patients with idiopathic dilated cardiomyopathy].

Purpose: The effects of ibopamine (IBO) on left ventricular (LV) mechanics and contractility have not been described. The aim of this study was to test the hypothesis that IBO has a contractile effect at a dose of 200 mg.

Methods: Ten male patients (43 +/- 7 years) with refractory heart failure due to idiopathic dilated cardiomyopathy were studied. The patients were submitted to simultaneous echo-Doppler and hemodynamic (microtip catheter) studies, before (B) and after (20, 40 and 60 minutes) a dose of 200 mg of IBO. LV pressure/diameter and stress/strain relations were obtained. Subsequently, heart rate (HR-bpm), cardiac output (CO-L/m), end-diastolic pressure (EDP-mmHg); fractional shortening (FS-%); maximal elastance (Emax-mmHg/cm/s); end systolic (ESS-g/cm2) and end-diastolic (EDS-g/cm2) stress; chamber (Kp-mmHg/cm) and muscle (K(m)-g/cm2) stiffness, and the time of constant relaxation (Tau-ms) were analyzed.

Results: Results were presented as mean +/- standard deviation for conditions before and after IBO (20, 40 and 60 minutes) respectively. There was no change in HR (99 +/- 7; 100 +/- 7; 99 +/- 8; 99 +/- 10). Significant increases were observed in CO (4.13 +/- 1.28; 4.95 +/- 1.38; 5.13 +/- 1.86; 5.18 +/- 1.57), FS (13.7 +/- 2.4; 15.4 +/- 2.8; 15.9 +/- 1.8; 16.1 +/- 2.0), and Emax (14.8 +/- 3.2; 16 +/- 3.6; 17.7 +/- 4.2; 17.6 +/- 4.2). A transient (20 minutes) increase followed by a decrease (40 and 60 minutes) occurred in EDP (26.3 +/- 4.2; 30.6 +/- 6.4; 24.6 +/- 5.6; 22.3 +/- 4.6), EDS (79.7 +/- 22.8; 91.7 +/- 29.6; 79 +/- 31; 63 +/- 17.3), and Kp (27.2 +/- 12.6; 60 +/- 26.7; 27.9 +/- 11.7; 28.1 +/- 11).

Conclusion: IBO has a beneficial effect on LV systolic and diastolic function as well as on contractility in patients with heart failure due to idiopathic dilated cardiomyopathy.